A method for storing carbon dioxide by strip mining of red mud based filling material bags in cooperation with mineralization under coal

Abstract

The present application belongs to the technical field of coal-under-aluminum goaf filling, and particularly relates to a method for filling and cooperatively mineralizing and storing carbon dioxide based on coal-under-aluminum strip mining and red mud-based filling material bag filling, which comprises the following steps: S1, arranging filling bags; S2, aluminum layer bottom plate grouting; S3, CO2 delivery; S4, red mud slurry injection; and S5, coal-aluminum layer interlayer grouting. Through aluminum layer bottom plate grouting and coal-aluminum layer interlayer grouting, the present application effectively prevents Ordovician water outburst and harmful substance infiltration into underground water, and simultaneously serves as a CO2 injection capping layer, thereby effectively increasing the mineralization amount of CO2. The main components of the red mud slurry are red mud, fly ash and crushed coal gangue, which can significantly reduce filling costs, effectively reduce solid waste accumulation and environmental pollution, realize resource recycling, and store the red mud in the flexible filling bag in the goaf. If the valuable elements in the red mud are urgently needed in the future, they can be mined out for extraction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of filling under coal aluminum goaf, in particular to a method for filling and mineralizing and sealing carbon dioxide based on strip mining of red mud filling material under coal aluminum. BACKGROUND

[0002] Red mud is a kind of strong alkaline solid industrial waste produced in the process of producing alumina from bauxite. Its high pH value and specific chemical composition make it face certain challenges in environmental protection and resource utilization. Therefore, how to effectively treat and utilize red mud, reduce its impact on the environment, and realize the resource utilization of red mud has become the focus of current and future research.

[0003] Coal under aluminum ore body is usually located under coal seam. For upstream bauxite mining, after the overlying coal seam is mined, the original rock stress field changes dramatically, and the stress redistribution caused by the roof caving of the coal seam goaf induces the roof fracture of the bauxite layer to be connected, forming a water channel or a risk of collapse. Therefore, coal under aluminum filling mining is the only way to ensure mine safety. Red mud, as a kind of solid waste, is one of the effective ways to treat red mud. Using red mud as filling material not only reduces environmental pollution but also realizes the secondary utilization of resources. SUMMARY

[0004] The present application provides a method for filling and mineralizing and sealing carbon dioxide based on strip mining of red mud filling material under coal aluminum to solve the problem of environmental hazards caused by large amount of red mud stacking and how to solve the problem of mineralizing and sealing carbon dioxide at the same time. The grouting layers of coal and aluminum interlayer and aluminum layer bottom plate form a multi-layer support structure with the strip aluminum column left by the strip mining of coal under aluminum, forming a carbon dioxide sealing layer to increase the amount of carbon dioxide mineralization, and the support structure also provides a guarantee for the safe mining of coal under aluminum bauxite.

[0005] To solve the above technical problems, the technical scheme adopted by the present application is as follows: a method for filling and mineralizing and sealing carbon dioxide based on strip mining of red mud filling material under coal aluminum, comprising the following steps:

[0006] S1, arranging filling bags: after the coal under aluminum layer is mined, the soft filling bags are arranged in the roof of the aluminum layer goaf in intervals, and the filling bags are connected in turn by hard material conveying pipelines;

[0007] S2, aluminum layer bottom plate grouting: drill grouting holes under the aluminum layer, and pump the grouting material into the grouting pipeline I by the grouting pump of the ground grouting station, and then push the grouting material into the aluminum layer bottom plate by the grouting pipeline I;

[0008] S3, CO2 delivery: the gas pipeline delivers CO2 from the CO2 pump station on the ground to the filling bag through the grouting pipeline II, and delivers CO2 to the red mud slurry mixing station;

[0009] S4, injection of red mud slurry: after mixing and stirring the red mud slurry on the ground through the red mud slurry mixing station, it is injected into the filling bag arranged in the aluminum layer goaf through the grouting pipeline II;

[0010] S5, coal-aluminum layer grouting: drill grouting holes in the middle layer between the coal seam and the aluminum layer, and pump the grouting material from the ground grouting station to the grouting pipeline I through the grouting pump, and inject it into the coal-aluminum layer.

[0011] As a further limitation of the technical scheme of the application, the step S1 is strip mining of the aluminum layer under the coal seam, the strip mining ratio is 3:1, the recovery rate is 75%, the strip aluminum column is not mined and is left as a support; the flexible filling bag contains a waterproof membrane to isolate the flow of internal and external liquids and gases; the filling bag is a rectangular cuboid with a size of 10m*10m*5m, the spacing distance between the filling bags is 10m, and the filling bags are connected by hard steel pipes with a diameter of 150mm.

[0012] As a further limitation of the technical scheme of the application, the step S2 is the aluminum layer under the coal seam; the grouting level of the aluminum layer floor is at a position 5-20m below the aluminum layer; the grouting material of the aluminum layer floor grouting layer is ordinary Portland cement slurry, which is pumped from the ground to the grouting pipeline I through the grouting pump, and then filled into the aluminum layer floor from the grouting hole. The aluminum layer floor grouting prevents Ordovician water from bursting out and prevents harmful substances from seeping into groundwater.

[0013] As a further limitation of the technical scheme of the application, in step S3, the grouting pipeline II delivers red mud slurry and CO2 gas, and first delivers CO2 gas for 30-60 minutes before starting to deliver red mud slurry, and the delivery process of red mud slurry is carried out in an environment filled with CO2 gas.

[0014] As a further limitation of the technical scheme of the application, in step S4, the red mud slurry is a mixed slurry prepared by mixing and stirring red mud, fly ash, desulfurization gypsum, cement, water, crushed coal gangue and injected CO2; the red mud slurry is delivered through the steel pipe pipeline between the filling bags; the mass ratio of red mud, fly ash, desulfurization gypsum, cement, crushed coal gangue is 3.5-6:5-6.5:0.75-1:1:4-6, CO2 is continuously injected during the stirring process of the red mud slurry, and the slurry concentration is 75%-83%. The red mud slurry is prepared into a cylindrical sample with a size of 50mm*100mm according to the above ratio, the 28d uniaxial compressive strength is 6-9MPa, the slump is 220mm, and the pH of the red mud slurry solution is 6.5-8.5.

[0015] As a further limitation of the technical scheme of the application, the ordinary portland cement slurry injected in steps S2 and S5 uses ordinary portland cement with a strength grade of 42.5, and the water-cement ratio is 0.5-0.7; the grouting holes in steps S2 and S5 are all opened by using a 219mm drill bit, a 133mm steel pipe is lowered as a mouth protection pipe, the outer wall of the mouth protection pipe is sealed and fixed with cement slurry, the lower part is drilled by using a 178mm drill bit until the bottom elevation of the hole, and then a 159mm flower pipe is used for pressure grouting.

[0016] As a further limitation of the technical scheme of the application, the coal-aluminum interlayer grouting layer in step S5 is above the coal layer and below the aluminum layer; the ordinary portland cement slurry is delivered by the grouting pipeline I; the grouting curtain after the coal-aluminum interlayer grouting layer is used as a carbon dioxide sealing top layer together with the mudstone layer above the aluminum layer; the horizontal position of the coal-aluminum interlayer grouting layer is vertically distant from the roof of the aluminum layer by more than 1.5 times the height of the fracture zone generated after the aluminum layer is excavated.

[0017] As a further limitation of the technical scheme of the application, the order of steps S4 and S5 can be interchanged.

[0018] As a further limitation of the technical scheme of the application, the aluminum layer bottom plate grouting and the coal-aluminum interlayer grouting in steps S2 and S5 are performed by using a multi-layer grouting mode, which further improves the grouting effect and sealing effect.

[0019] Compared with the prior art, the application has the following beneficial effects:

[0020] 1. The application effectively prevents the outburst of Ordovician limestone water and the infiltration of harmful substances into groundwater while serving as a sealing layer for the injection of CO2, thereby effectively increasing the mineralization amount of CO2.

[0021] 2. The main components of the red mud slurry are red mud, fly ash and crushed coal gangue, which significantly reduces the filling cost, effectively reduces the accumulation of solid waste and pollution to the environment, and realizes the recycling of resources.

[0022] 3. The red mud is sealed in the flexible filling bag in the goaf, and if the valuable elements in the red mud are needed in the future, they can be extracted again for extraction. BRIEF DESCRIPTION OF DRAWINGS

[0023] Fig. 1 It is a filling plane schematic diagram of the aluminum layer strip mining of the application.

[0024] Fig. 2 It is a filling arrangement profile of the coal under the aluminum layer working face of the application.

[0025] Fig. 3The figure shows the overall structure of the coal under the aluminum strip mining filling arrangement.

[0026] The figure is marked as follows:

[0027] 1-CO2 pump station; 2-red mud slurry mixing station; 3-grouting station; 4-grouting pipeline I; 5-grouting pipeline II; 6-gas pipeline; 7-grouting hole; 8-ground; 9-coal seam; 10-coal and aluminum interlayer grouting layer; 11-aluminum layer floor grouting layer; 12-mudstone layer; 13-aluminum layer; 14-filling bag; 15-strip aluminum column. DETAILED DESCRIPTION

[0028] The present application will be further described below in conjunction with specific examples.

[0029] As Figs. 1-3 shown, the present application provides a method for filling and mineralizing carbon dioxide based on coal under aluminum strip mining red mud-based filling material bag filling, the specific process steps are as follows:

[0030] S1: After the coal under the aluminum layer 13 mining working face, the soft filling bag 14 is arranged in the aluminum layer 13 goaf roof in sequence, and the filling bag 14 is connected with the hard material pipeline in sequence; the filling bag 14 is a cuboid with the size of 10m*10m*5m, the interval distance between the filling bag 14 and the filling bag 14 is 10 meters, and the hard steel pipe is connected in sequence; the waterproof film is adhered to the inside of the soft filling bag 14, which is used to isolate the slurry liquid of the red mud slurry deposited in the soft filling bag 14, underground water and the flow of CO2 filled; the strip mining recovery ratio is 3:1, the recovery rate is 75%, and the strip aluminum column 15 is not mined and reserved as support;

[0031] S2: drill grouting hole 7 under the aluminum layer 13, pump grouting material into grouting pipeline I 4 from ground grouting station 3 through grouting pump, then push grouting material into the aluminum layer floor from grouting pipeline I 4; the aluminum layer floor grouting layer 11 is located at 5~20 meters below the aluminum layer 13; the grouting material of the aluminum layer floor grouting layer 11 is ordinary Portland cement slurry with strength grade of 42.5, and the water-cement ratio is 0.6; pumped into the aluminum layer floor grouting layer 11 from the grouting hole 7 by the grouting pump through the grouting pipeline I 4 from the ground;

[0032] S3: the gas pipeline 6 transports CO2 from the CO2 pump station 1 of the ground 8 to the filling bag 14 through the grouting pipeline II 5 on one hand, and transports CO2 to the red mud slurry mixing station 2 on the other hand; first transport CO2 gas for 30min~60min, then start to transport red mud slurry, the transport process of red mud slurry is carried out in the environment filled with CO2 gas; grouting pipeline I 4 is used for transporting ordinary Portland cement slurry, and grouting pipeline II 5 is used for transporting red mud slurry and CO2 gas;

[0033] S4: After the red mud slurry is mixed and stirred by the red mud slurry mixing station 2 on the ground 8, the red mud slurry is injected into the filling bag 14 arranged in the goaf of the aluminum layer 13 through the grouting pipe II 5; the red mud slurry is a mixed slurry after mixing and stirring of red mud, fly ash, desulfurization gypsum, cement, water, and crushed coal gangue, and injected CO2, the proportion of the red mud slurry is red mud: fly ash: desulfurization gypsum: cement: crushed coal gangue = 4:6:0.75:1:4, CO2 is continuously injected during the stirring of the red mud slurry, and the slurry concentration is 78%; the filling bags are connected with each other by a hard seamless steel pipe, and the red mud slurry flows and is transported through the steel pipe between the filling bags 14.

[0034] S5: A grouting hole 7 is drilled in the middle layer between the coal seam 9 and the aluminum layer 13, the grouting material is pumped into the grouting pipe I 4 by the grouting pump of the ground grouting station 3, and is injected into the coal-aluminum interlayer grouting layer 10; the coal-aluminum interlayer grouting layer 10 is located at the upper layer of the coal seam 9 and the lower layer of the aluminum layer 13; after grouting, the grouting curtain of the coal-aluminum interlayer grouting layer 10 and the mudstone layer 12 on the upper part of the aluminum layer 13 serve as a carbon dioxide sealing top layer; the horizontal position of the coal-aluminum interlayer grouting layer 10 and the vertical distance between the top plate of the aluminum layer 13 are greater than 1.5 times the height of the fracture zone generated after the aluminum layer 13 is excavated.

[0035] In the method, the mineralization and absorption of CO2 are divided into two aspects: one is participating in the carbon fixation reaction in the red mud slurry mixing station on the ground, and the other is absorbing CO2 in the grouting pipe II and the flexible filling bag and the injected red mud slurry, so that CO2 is mineralized. Through the aluminum layer bottom plate grouting and the coal-aluminum interlayer grouting, the outburst of the Ordovician limestone water and the infiltration of harmful substances into the underground water are effectively prevented, and the sealing layer for injecting CO2 is formed, so that the mineralization amount of CO2 is effectively increased.

[0036] The main components of the red mud slurry are red mud, fly ash, and crushed coal gangue, which can significantly reduce the filling cost, effectively reduce the accumulation of solid waste and pollution to the environment, and realize the recycling and utilization of resources.

Claims

1. A method for the sequestration of carbon dioxide by the simultaneous mineralization of coal seam gas emissions and coal mine waste rock through the use of a red mud based filling material strip mined under coal seams and packed in bags, characterised in that, It comprises the following steps: S1, the arrangement of filling bags: after the mining of the aluminum layer under the coal, the soft filling bags are arranged in the roof of the aluminum layer goaf, and the filling bags are connected in sequence by the hard material conveying pipeline; S2, grouting of the aluminum layer floor: drill grouting holes under the aluminum layer, and pump the grouting material into the grouting pipeline I by the grouting pump of the ground grouting station, then push the grouting material into the aluminum layer floor by the grouting pipeline I; the aluminum layer is the aluminum layer under the coal seam; the grouting layer of the aluminum layer floor is located at the position 5-20 meters below the aluminum layer; S3, CO2 delivery: the gas pipeline delivers CO2 to the filling bag from the CO2 pump station on the ground through the grouting pipeline II, and delivers CO2 to the red mud slurry mixing station; the grouting pipeline II delivers red mud slurry and CO2 gas, and first delivers CO2 gas for 30-60 minutes before delivering red mud slurry, and the delivery process of red mud slurry is carried out in the environment filled with CO2 gas; S4, injection of red mud slurry: after mixing and stirring the red mud slurry by the red mud slurry mixing station on the ground, the red mud slurry is injected into the filling bags arranged in the aluminum layer goaf through the grouting pipeline II; the red mud slurry is a mixed slurry obtained by mixing and stirring red mud, fly ash, desulfurization gypsum, cement, water, crushed coal gangue and injected CO2; the mass ratio of red mud, fly ash, desulfurization gypsum, cement and crushed coal gangue is 3.5-6:5-6.5:0.75-1:1:4-6, and CO2 is continuously injected during the mixing and stirring of the red mud slurry, and the slurry concentration is 75%-83%; S5, grouting between coal and aluminum layers: drill grouting holes at the middle layer between the coal seam and the aluminum layer, and pump the grouting material into the grouting pipeline I by the grouting pump of the ground grouting station, and inject it into the coal and aluminum layer; the vertical distance between the horizontal position of the coal and aluminum layer grouting layer and the aluminum layer roof is greater than 1.5 times the height of the crack zone generated after the excavation of the aluminum layer.

2. The method for simultaneous mineralization and sequestration of carbon dioxide by coal-under-aluminum-strip-mining red mud-based filling material bag filling according to claim 1, characterized in that, The coal under the aluminum layer in step S1 is strip mined, the strip mining ratio is 3:1, the recovery rate is 75%, the strip aluminum column is not mined and is left as support; the soft filling bag contains a waterproof membrane; the filling bag is a rectangular cuboid with a size of 10m*10m*5m, the distance between the filling bags is 10 meters, the filling bags are connected by a hard steel pipe, and the steel pipe is a cylindrical seamless steel pipe with a diameter of 150mm.

3. The method for simultaneous mineralization and sequestration of carbon dioxide by coal-under-aluminum-strip-mining red mud-based filling material bag filling according to claim 1, characterized in that, The grouting material of the aluminum layer floor grouting layer is ordinary Portland cement slurry, which is pumped into the grouting pipeline I by the grouting pump from the ground, and then filled into the aluminum layer floor from the grouting hole.

4. The method for simultaneous mineralization and sequestration of carbon dioxide by coal-under-aluminum-strip-mining red mud-based filling material bag filling according to claim 1, characterized in that, The ordinary Portland cement slurry injected in steps S2 and S5 uses ordinary Portland cement with a strength grade of 42.5, and the water-cement ratio is 0.5-0.7; the grouting holes in steps S2 and S5 are all opened by 219mm drill bits, 133mm steel pipes are lowered as mouth protection pipes, the outer wall of the mouth protection pipe is sealed with cement slurry, the lower part is drilled by a 178mm drill bit until the bottom elevation, and then 159mm flower pipe pressure grouting is used.

5. The method of claim 1, wherein the method is characterized in that, The coal-aluminum interlayer grouting layer position described in step S5 is that the coal layer is at the upper position and the aluminum layer is at the lower position; the coal-aluminum interlayer grouting is ordinary Portland cement slurry delivered by the grouting pipeline I; the grouting curtain after the coal-aluminum interlayer grouting and the mudstone layer at the upper part of the aluminum layer serve as the carbon dioxide closed top layer.

6. The method of claim 1, wherein the method is characterized by, The sequence of step S4 and step S5 can be interchanged.

7. The method of claim 1, wherein the method is characterized by, The aluminum layer bottom plate grouting and the coal-aluminum interlayer grouting in steps S2 and S5 are carried out in a multi-layer grouting mode.

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